package com.kantboot.wechat.applet.util;

import org.apache.commons.codec.binary.Base64;
import org.bouncycastle.jce.provider.BouncyCastleProvider;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.io.UnsupportedEncodingException;
import java.security.*;
import java.security.spec.InvalidParameterSpecException;
import java.util.Arrays;

/**
 * Created by yfs on 2018/3/25.
 * <p>
 * AES-128-CBC 加密方式
 * 注：
 * AES-128-CBC可以自己定义“密钥”和“偏移量“。
 * AES-128是jdk自动生成的“密钥”。
 *
 * @author 佚名
 */
public class AesCbcUtil {


    static {
        //BouncyCastle是一个开源的加解密解决方案，主页在http://www.bouncycastle.org/
        Security.addProvider(new BouncyCastleProvider());
    }

//    /**
//     * AES解密
//     *
//     * @param data           //密文，被加密的数据
//     * @param key            //秘钥
//     * @param iv             //偏移量
//     * @param encodingFormat //解密后的结果需要进行的编码
//     * @return
//     * @throws Exception
//     */
//    public static String decrypt(String data, String key, String iv, String encodingFormat) throws Exception {
////        initialize();
//
//        //被加密的数据
//        byte[] dataByte = Base64.decodeBase64(data);
//        //加密秘钥
//        byte[] keyByte = Base64.decodeBase64(key);
//        //偏移量
//        byte[] ivByte = Base64.decodeBase64(iv);
//
//
//        try {
//            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
//
//            SecretKeySpec spec = new SecretKeySpec(keyByte, "AES");
//
//            AlgorithmParameters parameters = AlgorithmParameters.getInstance("AES");
//            parameters.init(new IvParameterSpec(ivByte));
//
//            cipher.init(Cipher.DECRYPT_MODE, spec, parameters);// 初始化
//
//            byte[] resultByte = cipher.doFinal(dataByte);
//            if (null != resultByte && resultByte.length > 0) {
//                String result = new String(resultBytencodingFormat);
//                return result;
//            }
//            return null;
//        } catch (NoSuchAlgorithmException e) {
//            e.printStackTrace();
//        } catch (NoSuchPaddingException e) {
//            e.printStackTrace();
//        } catch (InvalidParameterSpecException e) {
//            e.printStackTrace();
//        } catch (InvalidKeyException e) {
//            e.printStackTrace();
//        } catch (InvalidAlgorithmParameterException e) {
//            e.printStackTrace();
//        } catch (IllegalBlockSizeException e) {
//            e.printStackTrace();
//        } catch (BadPaddingException e) {
//            e.printStackTrace();
//        } catch (UnsupportedEncodingException e) {
//            e.printStackTrace();
//        }
//
//        return null;
//    }



    public static String decrypt(String encryptedData, String sessionKey, String iv) throws Exception {
        String result = "";
        // 被加密的数据
        byte[] dataByte = Base64.decodeBase64(encryptedData);
        // 加密秘钥
        byte[] keyByte = Base64.decodeBase64(sessionKey);
        // 偏移量
        byte[] ivByte = Base64.decodeBase64(iv);
        try {
            // 如果密钥不足16位，那么就补足. 这个if 中的内容很重要
            int base = 16;
            if (keyByte.length % base != 0) {
                int groups = keyByte.length / base + (keyByte.length % base != 0 ? 1 : 0);
                byte[] temp = new byte[groups * base];
                Arrays.fill(temp, (byte) 0);
                System.arraycopy(keyByte, 0, temp, 0, keyByte.length);
                keyByte = temp;
            }
            // 初始化
            Security.addProvider(new BouncyCastleProvider());
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding", "BC");
            SecretKeySpec spec = new SecretKeySpec(keyByte, "AES");
            AlgorithmParameters parameters = AlgorithmParameters.getInstance("AES");
            parameters.init(new IvParameterSpec(ivByte));
            // 初始化
            cipher.init(Cipher.DECRYPT_MODE, spec, parameters);
            byte[] resultByte = cipher.doFinal(dataByte);
            if (null != resultByte && resultByte.length > 0) {
                result = new String(resultByte, "UTF-8");
            }
        } catch (NoSuchAlgorithmException e) {
            System.err.println(e.getMessage());
        } catch (NoSuchPaddingException e) {
            System.err.println(e.getMessage());
        } catch (InvalidParameterSpecException e) {
            System.err.println(e.getMessage());
        } catch (IllegalBlockSizeException e) {
            System.err.println(e.getMessage());
        } catch (BadPaddingException e) {
            System.err.println(e.getMessage());
        } catch (UnsupportedEncodingException e) {
            System.err.println(e.getMessage());
        } catch (InvalidKeyException e) {
            System.err.println(e.getMessage());
        } catch (InvalidAlgorithmParameterException e) {
            System.err.println(e.getMessage());
        } catch (NoSuchProviderException e) {
            System.err.println(e.getMessage());
        }
        return result;
    }
}